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The article presents the discussion on causes and Countermeasures of soil fatigue. Topics include soil fatigue being intentionally induced on central test plots in order for examining the causes of the replica disease and to be able to check the effectiveness of possible solutions; and extent soil properties contributing to the intensity of soil fatigue and extent the soil quality and material cycles.

Soil moisture is an essential climate variable of the Earth system. Understanding its spatiotemporal dynamics is essential for predicting weather patterns and climate variability, monitoring and mitigating the effects and occurrence of droughts and floods, improving irrigation in agricultural areas, and sustainably managing water resources. Here we review in depth how soils can remember information on soil moisture anomalies over time, as embedded in the concept of soil moisture memory (SMM). We explain the mechanisms underlying SMM and explore its external and internal drivers; we also discuss the impacts of SMM on different land surface processes, focusing on soil‐plant‐atmosphere coupling. We explore the spatiotemporal variability, seasonality, locality, and depth‐dependence of SMM and provide insights into both improving its characterization in land surface models and using satellite observations to quantify it. Finally, we offer guidance for further research on SMM. Our review paper takes an in‐depth look at soil moisture memory, which is how soil records its moisture history over time and space. Analogous to human psychology, which seeks to understand how a person's/society's memory influences his/her present and future behavior, understanding soil moisture memory encourages consideration of how such memory determines present state and might determine future behavior of soils exposed to environmental disturbances. Soil moisture memory can be affected by a variety of factors, both external (e.g., weather extremes) and internal (soil's unique properties). It affects everything from the air to the way our landscapes respond to disasters like droughts, wildfires, and floods. We also studied how this phenomenon affects the balance of water and energy in our environment, the health of our plants, and even how it communicates with the atmosphere. We show how it can change depending on where you are on the planet, the time of year, and how deep you dig into the soil. We offer scientists insights into how weather and land surface models can become more accurate by accounting for soil moisture memory. Its understanding not only helps us predict and manage our environment, but also provides opportunities for exciting scientific discoveries. Atmospheric forcings, land use and management, and soil processes and mechanisms explain how and why soil moisture memory emerges in ecosystemsNonlocality of moisture memory, its spread across different regions, and its interaction with large‐scale climate phenomena are underexploredFurther advances in land surface models and closer integration of model simulations and observations are needed to better characterize moisture memory Atmospheric forcings, land use and management, and soil processes and mechanisms explain how and why soil moisture memory emerges in ecosystems Nonlocality of moisture memory, its spread across different regions, and its interaction with large‐scale climate phenomena are underexplored Further advances in land surface models and closer integration of model simulations and observations are needed to better characterize moisture memory

Often large quantities of plastics are found in compost, with price look-up stickers being a major but little-explored component in the contamination path. Stickers glued to fruit or vegetable peels usually remain attached to the organic material despite sorting processes in the composting plant. Here, we investigated the effects of industrial composting on the structural alterations of these stickers. Commercial polypropylene (PP) stickers on banana peels were added to a typical organic material mixture for processing in an industrial composting plant and successfully resampled after a prerotting (11 days) and main rotting step (25 days). Afterward, both composted and original stickers were analyzed for surface and structural changes via scanning electron microscopy, Fourier-transform infrared spectroscopy, and micro- and nano-X-ray computed tomography (CT) combined with deep learning approaches. The composting resulted in substantial surface changes and degradation in the form of microbial colonization, deformation, and occurrence of cracks in all stickers. Their pore volumes increased from 16.7% in the original sticker to 26.3% at the end of the compost process. In a similar way, the carbonyl index of the stickers increased. Micro-CT images additionally revealed structural changes in the form of large adhesions that penetrated the surface of the sticker. These changes were accompanied by delamination after 25 days of composting, thus overall hinting at the degradation of the stickers and the subsequent formation of smaller microplastic pieces.

Environmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary health. Despite global efforts to mitigate legacy pollutants, the continuous introduction of new substances remains a major threat to both people and the planet. In response, global initiatives are focusing on risk assessment and regulation of emerging contaminants, as demonstrated by the ongoing efforts to establish the UN’s Intergovernmental Science-Policy Panel on Chemicals, Waste, and Pollution Prevention. This review identifies the sources and impacts of emerging contaminants on planetary health, emphasizing the importance of adopting a One Health approach. Strategies for monitoring and addressing these pollutants are discussed, underscoring the need for robust and socially equitable environmental policies at both regional and international levels. Urgent actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.

Compared with the ever-growing information about the anthropogenic discharge of nutrients, metals, and antibiotics on the disturbance of antibiotic resistance genes (ARGs), less is known about how the potential natural stressors drive the evolutionary processes of antibiotic resistance. This study examined how soil resistomes evolved and differentiated over 30 years in various land use settings with spatiotemporal homogeneity and minimal human impact. We found that the contents of soil organic carbon, nitrogen, soil microbial biomass, and bioavailable heavy metals, as well as related changes in the antibiotic resistome prevalence including diversity and abundance, declined in the order of grassland > cropland > bareland. Sixty-nine remaining ARGs and 14 mobile genetic elements (MGEs) were shared among three land uses. Multiple factors (i.e., soil properties, heavy metals, bacterial community, and MGEs) contributed to the evolutionary changes of the antibiotic resistome, wherein the resistome profile was dominantly driven by MGEs from both direct and indirect pathways, supported by a partial least-squares path model analysis. Our results suggest that pathways to mitigate ARGs in soils can coincide with land degradation processes, posing a challenge to the common goal of managing our environment sustainably.

Common farming practices in sub-Saharan Africa (SSA) such as intensive and repeated tillage, complete crop residue removal, and biomass burning create risks of soil degradation. To reduce these risks, conservation agriculture (CA) uses minimal soil disturbance, crop residue retention, and crop rotation in order to reduce soil erosion, improve soil quality and crop production, and facilitate climate change mitigation and adaptation. Nevertheless, CA adoption in SSA is extremely low. This paper aims to review current practices, challenges, and constraints to the adoption of CA in SSA. Our analyses show that CA is practiced in only about 1.25% of the total cultivated area in SSA, despite two decades of efforts to promote CA adoption among smallholder farmers. Specific difficulties in CA adoption by smallholder farmers in SSA may be attributed to i) lack of locally adaptable CA systems, particularly those integrating the needs of livestock production; ii) lack of adequate crop residues for surface mulch; iii) inconsistent and low crop yields; iv) lack of smallholder CA equipment for direct sowing; v) limited availability, high cost, and inadequate knowledge associated with the use of appropriate fertilizer and herbicides; and vi) lack of CA knowledge and training. Other problems relate to the management of specific soil orders, e.g., CA implementation on steeply sloping land and poorly drained soils such as Vertisols. CA adoption by smallholder farmers is also obstructed by socio-economic factors due to smallholder farmers’ focus on short term yield increases and their lack of access to markets, loans, and education. To facilitate wider adoption by smallholder farmers in SSA, CA approaches should be downscaled to fit the existing tillage tools and the specific agroecological and socio-economic farm settings.

31P nuclear magnetic resonance (NMR) spectra can be biased due to the hydrolysis of labile P species during sample treatment and NMR analysis. This paper offers an approach to circumvent this problem by performing sample preparation and analysis in 18O-enriched medium. Heavy 18O isotope atoms were introduced into the resulting artificial hydrolysis products. The NMR signal of 18O-labeled P was shifted upfield relative to the unlabeled P nuclei in natural metabolites. This isotope shift enabled an immediate differentiation of artificial hydrolysis products from natural metabolites. Moreover, the hydrolysis products could be accurately quantified. Our data suggest that the extent to which artificial hydrolysis alters NMR spectra varies among different types of environmental samples. For instance, 72–84% of the detected monoesters in the organic soils of this study were actually artificially hydrolyzed diesters. By contrast, artificial hydrolysis products in the mineral soils used for this study accounted for less than 6% of the total monoesters. Polyphosphate was also hydrolyzed to yield 18O-labeled products in algal biomass.

Agricultural management is a key force affecting soil processes and functions. Triggered by biophysical constraints as well as rapid structural and technological developments, new management practices are emerging with largely unknown impacts on soil processes and functions. This impedes assessments of the potential of such emerging practices for sustainable intensification, a paradigm coined to address the growing demand for food and nonfood products. In terms of soil management, sustainable intensification means that soil productivity is increased while other soil functions and services, such as carbon storage and habitat for organisms, are simultaneously maintained or even improved. In this paper we provide an overview of research challenges to better understand how emerging soil management practices affect soil processes and functions.

Lake sediments are unique archives of human environment interactions. Lake Prespa is one of the oldest lakes in Europe, lying in the southwestern Balkans and thus on a possible dispersal route of anatomically modern humans from Africa. In this study, we investigated the effects of climate, vegetation and human activity on fire over the last 92,000 years in this region. Sediment samples were taken from Lake Prespa, and nearby Lake Ohrid for comparison of the regional relevance, and analyzed for benzene polycarboxylic acids as markers for burned organic carbon residues (black carbon, BC). Peaking contents of BC (up to 1 g BC kg−1sediment) coincided with warm and humid phases, when forests expanded at marine isotope stages (MIS) 5 and 1. During the colder and more arid climates of MIS 4 and 2, BC contents were lowered by a factor of 10, with a distinct minimum during the Last Glacial Maximum (0.07 g BC kg−1). The ratio of pentacarboxylic acid to mellitic acid (B5CA/B6CA) declined from 1.2 at MIS 5 to values of 0.3 at MIS 2, confirming a change in fire regime. Overall, BC contents peaked at cycles of solar radiation, vegetation composition and fuel availability, and thus correspond to the BC signal of other environmental archives. However, in the Late Holocene and as a result of human sedentary settlement, BC production increased, independent of decreasing insolation forcing. First black carbon record of the Dessarate (Ohrid‐Prespa) Lake regionFire activity over the past 92,000 years has been highest during periods of warm/humid climate and forest vegetation First black carbon record of the Dessarate (Ohrid‐Prespa) Lake region Fire activity over the past 92,000 years has been highest during periods of warm/humid climate and forest vegetation

The stable 13C/12C isotope composition usually varies among different organic materials due to isotope fractionation during biochemical synthesis and degradation processes. Here, we introduce a novel laser ablation-isotope ratio mass spectrometry (LA-IRMS) methodology that allows highly resolved spatial analysis of carbon isotope signatures in solid samples down to a spatial resolution of 10 μm. The presented instrumental setup includes in-house-designed exchangeable ablation cells (3.8 and 0.4 mL, respectively) and an improved sample gas transfer, which allow accurate δ13C measurements of an acryl plate standard down to 0.6 and 0.4 ng of ablated carbon, respectively (standard deviation 0.25‰). Initial testing on plant and soil samples confirmed that microheterogeneity of their natural 13C/12C abundance can now be mapped at a spatial resolution down to 10 μm. The respective δ13C values in soils with C3/C4 crop sequence history varied by up to 14‰ across a distance of less than 100 μm in soil aggregates, while being partly sorted along rhizosphere gradients of <300 μm from Miscanthusplant roots into the surrounding soil. These very first demonstrations point to the appearance of very small metabolic hotspots originating from different natural isotope discrimination processes, now traceable via LA-IRMS.

There is currently relatively little available information on subsoil phosphorus (P) use for crop production as a function of soil order. In this study, a rhizobox experiment was performed using subsoils of two reference soil groups, an Orthic Ferralsol and a Haplic Luvisol. To evaluate the immediate P uptake by wheat (Triticum aestivum L.) from different subsoil P pools during 14 days of growth, subsoil bands were spiked with KH2PO4 solution associated to Fe-hydroxide (33P-Fe), to Al-hydroxide (33P-Al), in free form (33P-OrthoP), or in trace amounts without any additional 31P (33P-NoP). At the beginning of the experiment, the soil water content was set at 75% of water-holding capacity, corresponding to an initial soil matric potential of −12 ± 1 kPa. During plant growth, soil moisture decreased in both soils, but soil matric potentials in both soils did not drop below field capacity (−33 kPa; pF 2.5). The shoot dry weights of the Ferralsol were 1.2 to 1.8 times those of the Luvisol. Despite elevated soil P availability in the Luvisol, shoot P concentrations did not differ between the two soils. The amount of 33P taken up by the shoots from the oxide phases was 15% to 40% greater in the Ferralsol treatments than in those in the Luvisol treatments. It was concluded that the more favourable physical soil conditions facilitated 33P uptake from both oxidic phases from the Ferralsol subsoil relative to the Luvisol subsoil, despite better P phytoavailability in the latter.

Core IdeasInfluence of climate on phosphorus dynamics in soil.Regression analyses for climosequence in Great Plains.Influence of cultivation and size fractions on phosphorus dynamics. The climatic regime influences the turnover of P in soils, resulting in shifts in P fractions of different bonding forms. Here, we aimed at (i) identifying possible changes in P fractions as related to mean annual temperature (MAT) and mean annual precipitation (MAP), as well as (ii) elucidating how these patterns change under long‐term agriculture. We analyzed different P fractions after sequential extraction according to the Hedley procedure from the top 10 cm of 18 native grassland sites and adjacent long‐term agricultural fields along a temperature and precipitation transect from central Saskatoon to south Texas. The analyses were performed on bulk soils and clay fractions. The results showed that total P (Ptot) concentrations decreased with increasing MAT but were not clearly related to MAP. The contributions of total inorganic P (Pitot) and total organic P (Potot) to Ptotdid neither change with MAT nor with MAP. The proportions of individual soil fractions were shifted from the labile and easily extractable P bonding forms to the more stable, residual P fractions with increasing annual temperature. Arable cropping induced loss of organic P (Po). The relationships to the climatic factors were sustained for the arable soil, but better reflected in the clay fractions than in the bulk soil. We conclude that there is a gross pattern of soil P distribution related to the climate, likely reflecting the increased biological processing as well as and progressing weathering and neoformation of secondary mineral phases as annual temperatures rise.

Countries in the Middle Eastern and North African (MENA) region are among the most water-scarce regions in the world, and their dryland soils are usually poor in organic carbon content (<0.5%). In this study, we summarize examples of how people in the few oases of the MENA region overcome environmental challenges by sustainably managing economically important date production. On the basis of the limited studies found in the existing literature, this mini-review focuses on the role of traditional soil organic matter amendments beneath the soil surface as a key tool in land restoration. We conclude that soil organic matter amendments can be very successful in restoring soil water and preventing the soil from salinization.

Due to the limited solubility of phosphorus (P) in soil, understanding its binding in fine colloids is vital to better forecast P dynamics and losses in agricultural systems. We hypothesized that water‐dispersible P is present as nanoparticles and that iron (Fe) plays a crucial role for P binding to these nanoparticles. To test this, we isolated water‐dispersible fine colloids (WDFC) from an arable topsoil (Haplic Luvisol, Germany) and assessed colloidal P forms after asymmetric flow field‐flow fractionation coupled with ultraviolet and an inductively coupled plasma mass spectrometer, with and without removal of amorphous and crystalline Fe oxides using oxalate and dithionite, respectively. We found that fine colloidal P was present in two dominant sizes: (i) in associations of organic matter and amorphous Fe (Al) oxides in nanoparticles <20 nm, and (ii) in aggregates of fine clay, organic matter and Fe oxides (more crystalline Fe oxides) with a mean diameter of 170 to 225 nm. Solution 31P‐nuclear magnetic resonance spectra indicated that the organically bound P predominantly comprised orthophosphate‐monoesters. Approximately 65% of P in the WDFC was liberated after the removal of Fe oxides (especially amorphous Fe oxides). The remaining P was bound to larger‐sized WDFC particles and Fe bearing phyllosilicate minerals. Intriguingly, the removal of Fe by dithionite resulted in a disaggregation of the nanoparticles, evident in higher portions of organically bound P in the <20 nm nanoparticle fraction, and a widening of size distribution pattern in larger‐sized WDFC fraction. We conclude that the crystalline Fe oxides contributed to soil P sequestration by (i) acting as cementing agents contributing to soil fine colloid aggregation, and (ii) binding not only inorganic but also organic P in larger soil WDFC particles. Improved quantification of P bonding forms in soil nanoparticles and their aggregates.Most P in water dispersible fine colloids is associated with (amorphous) Fe oxides.Crystalline Fe oxides contribute to soil P sequestration.Crystalline Fe oxides act as cementing agents of aggregation for soil fine colloids.Crystalline Fe oxides bind not only inorganic but also organic P in larger soil colloid particles.

Wastewater irrigation is often performed by flood irrigation, leading to changes in redox potential (Eh) of irrigated soils. In addition to soil organic matter, Fe‐(hydr)oxides are important sorbents for pollutants, and biotransformation of pollutants can be accelerated under reducing conditions. Here, the influence of reducing conditions on the release of sorbed pharmaceuticals from soil and their potential accelerated dissipation was investigated in a microcosm study. Samples of a soil from the Mezquital Valley (Mexico) irrigated for 85 yr with untreated wastewater were incubated under oxidizing (Eh of 500 ± 20 mV), weakly reducing (Eh of 100 ± 20 mV), and moderately reducing (Eh of −100 ± 20 mV) soil conditions for 30 to 31 d. The concentrations of nine pharmaceuticals (bezafibrate, carbamazepine, ciprofloxacin, sulfamethoxazole, trimethoprim, enrofloxacin, clarithromycin, diclofenac, and naproxen) were extracted via solid‐phase extraction from soil slurries and analyzed by liquid chromatography–tandem mass spectrometry. Low Eh did not lead to a release of formerly sorbed pharmaceuticals from the wastewater irrigated soil. High pH values (>8) of the examined soil resulting from denitrification under reducing conditions prevented the dissolution of Fe‐(hydr)oxides and, hence, the potential release of pharmaceuticals. A trend of decreasing concentrations of sulfamethoxazole and bezafibrate with time under moderately reducing conditions supports previous findings of a transformation of these compounds under anaerobic conditions.

•First-time analyses of black carbon in 120,000 year old archaeological deposits.•Black carbon inputs highlight phases of increased human habitability and fuel availability.•Hot fires in the Pleistocene indicate human presence in Sodmein Cave.

Variations in soil moisture and surface roughness are major obstacles for the proximal sensing of soil organic C (SOC) using visible and near‐infrared spectroscopy (VIS‐NIRS). We gained a significant improvement of SOC prediction under field conditions with a stepwise approach. This comprised of (i) the estimation of these disturbing factors and (ii) the subsequent use of this information in multivariate SOC prediction. We took 120 surface soil samples (SOC contents 6.55–13.40 g kg−1) from a long‐term trial near Bonn, Germany. To assess soil moisture, we recorded VIS‐NIR spectra on <2‐mm sieved disturbed samples at seven different moisture levels (air‐dried to 30% w/w). The impact of roughness on VIS‐NIRS performance was studied with undisturbed samples (air‐dried and at different moisture levels), which were scanned with a laser profiler after fractionation into six aggregate size classes. The results confirmed that it was possible to include VIS‐NIRS based assessments of soil moisture [R2adj= 0.96; root mean square error of cross validation (RMSEcv) = 1.99% w/w] into the prediction of SOC contents for sieved samples <2 mm (R2adj= 0.81–0.94; RMSEp= 0.41–0.72 g SOC kg−1). However, for rough soil surfaces, SOC contents were overestimated, and the prediction of roughness indices using VIS‐NIRS failed. Fortunately, surface roughness did not impair the VIS‐NIRS assessment of soil moisture. Hence, we could directly estimate moisture via VIS‐NIRS in undisturbed field samples and then incorporate this information into a moisture‐dependent prediction of SOC contents. This provided accurate SOC estimates for field‐moist, undisturbed samples (R2adj= 0.91). Deviations from the reference method (elemental analysis) were below 2 g SOC kg−1.

Biochar applications to soils can improve soil fertility by increasing the soil's cation exchange capacity (CEC) and nutrient retention. Because biochar amendment may occur with the applications of organic fertilizers, we tested to which extent composting with farmyard manure increases CEC and nutrient content of charcoal and gasification coke. Both types of biochar absorbed leachate generated during the composting process. As a result, the moisture content of gasification coke increased from 0.02 to 0.94 g g−1, and that of charcoal increased from 0.03 to 0.52 g g−1. With the leachate, the chars absorbed organic matter and nutrients, increasing contents of water‐extractable organic carbon (gasification coke: from 0.09 to 7.00 g kg−1; charcoal: from 0.03 to 3.52 g kg−1), total soluble nitrogen (gasification coke: from not detected to 705.5 mg kg−1; charcoal: from 3.2 to 377.2 mg kg−1), plant‐available phosphorus (gasification coke: from 351 to 635 mg kg−1; charcoal: from 44 to 190 mg kg−1), and plant‐available potassium (gasification coke: from 6.0 to 15.3 g kg−1; charcoal: from 0.6 to 8.5 g kg−1). The potential CEC increased from 22.4 to 88.6 mmolckg−1for the gasification coke and from 20.8 to 39.0 mmolckg−1for the charcoal. There were little if any changes in the contents and patterns of benzene polycarboxylic acids of the biochars, suggesting that degradation of black carbon during the composting process was negligible. The surface area of the biochars declined during the composting process due to the clogging of micropores by sorbed compost‐derived materials. Interactions with composting substrate thus enhance the nutrient loads but alter the surface properties of biochars.

The environmental risks caused by the use of fluoroquinolone antibiotics in human therapeutics and animal husbandry are associated with their persistence and (bio)accessibility in soil. To assess these aspects, we administered difloxacin to pigs and applied the contaminated manure to soil. We then evaluated the dissipation and sequestration of difloxacin in soil in the absence and presence of plants within a laboratory trial, a mesocosm trial, and a field trial. A sequential extraction yielded antibiotic fractions of differing binding strength. We also assessed the antibiotic's effects on nitrogen turnover in soil (potential nitrification and denitrification). Difloxacin was hardly (bio)accessible and was very persistent under all conditions studied (dissipation half‐life in bulk soil, >217 d), rapidly forming nonextractable residues. Although varying environmental conditions did not affect persistence, dissipation was accelerated in soil surrounding plant roots. Effects on nitrogen turnover were limited due to the compound's strong binding and small (bio)accessibility despite its persistence.

Quantitative information about the amount and stability of organic carbon (OC) in different soil organic-matter (OM) fractions and in specific organic compounds and compound-classes is needed to improve our understanding of organic-matter sequestration in soils. In the present paper, we summarize and integrate results performed on two different arable soils with continuous maize cropping (a) Stagnic Luvisol with maize cropping for 24 y, b) Luvic Phaeozem with maize cropping for 39 y) to identify (1) the storage of OC in different soil organic-matter fractions, (2) the function of these fractions with respect to soil-OC stabilization, (3) the importance and partitioning of fossil-C deposits, and (4) the rates of soil-OC stabilization as assessed by compound-specific isotope analyses. The fractionation procedures included particle-size fractionation, density fractionation, aggregate fractionation, acid hydrolysis, different oxidation procedures, isolation of extractable lipids and phospholipid fatty acids, pyrolysis, and the determination of black C. Stability of OC was determined by 13C and 14C analyses. The main inputs of OC were plant litter (both sites) and deposition of fossil C likely from coal combustion and lignite dust (only Phaeozem).

Black Mollisols are typically rich in charred organic matter, however, little is known about the zonal distribution of black C (BC) in steppe soils. In this study, we used benzene polycarboxylic acids (BPCA) as specific markers for BC in particle-size fractions of depth profiles in several zonal soils (Greyzem, Phaeozem, Chernozem, Kastanozem) of the Russian steppe. In addition, liquid-state 13C-NMR spectra were obtained on the alkaline-soluble soil organic matter (SOM). The results showed that both the content and depth distribution of BC varies in the different soil types; the concentration of BC in the bulk top soils being closely related to the aromaticity of the SOM (r2 = 0.98 for the native topsoils, 0.83 for top- and subsurface soils). Especially the Chernozems were rich in aromatic SOM, which partly contained more than 17% BC of total C, most of which being allocated in the mineral fractions. Long-term arable cropping did not reduce the BC contents of the surface soil, though it did promote the enrichment of BC in the silt fractions. The same shift was detected as soil depth increased. We conclude that BC is not fully inert in these soils, but apparently can be preserved in the silt as decomposition of SOM increased, i.e., it accumulates exactly in that fraction, which has been formerly assigned to contain old, aromatic C.

Cattle dung contributes to hot-spot inputs of nutrients to grassland systems, but not much is known about its organic P (Po) composition and fate in the grassland soils. We used 31Phosphorus (P)–Nuclear Magnetic–Resonance (NMR) spectroscopy of alkaline soil extracts to examine potentials for tracing of different functional Po forms into a temperate grassland soil amended with dung. The proportion of monoester, DNA-diester, and phospholipid+teichoic acid P were comparable in dung extracts, but the soil was dominated by monoester P. The temporal trends in the DNA-diester P–to–monoester P (DDNAM) and diester P–to–monoester P (DM) ratio of dung, native soil, and soil amended with dung were monitored in the 70 d field experiment. The DDNAM and DM ratio in the dung-amended soil (0–1 and 1–5 cm depth) were always intermediate between the dung and (unamended) control soil. Clearly, extracted soil P was a mixture of incorporated dung-derived P and native soil P. The dung-P contribution in the 0–1 cm samples peaked at 47% of the total extracted P at day 70 and at 15% after 42 d in the 1–5 cm soil depth (based on the DM ratio). The proportions of dung-derived P and C in the soil were positively correlated with: 1) topsoil, using the DDNAM ratio (r2 = 0.975), and 2) top- and subsoil, using the DM ratio (r2 = 0.656). We concluded that our DDNAM and DM-P ratios approach (obtained from solution-31P NMR) did trace successfully the short-term dynamics and fate of dung Po in soil. It indicated that dung-derived Po varied as rapidly in soil as the dung-derived C.

An important feature of maintaining the agricultural stability in millennia-old mountain oases of northern Oman is the temporary abandonment of terraces. To analyse the effects of a fallow period on soil microbial performance, i.e. microbial activity and microbial biomass, samples of eight terrace soils abandoned for different periods were collected in situ, assigned to four fallow age classes and incubated for 30 days in the laboratory after rewetting. The younger fallow age classes of 1 and 5 years were based on the records of the farmers’ recollections, the two older fallow age classes of 10–20 and 25–60 years according to the increase in the d -to- l ratio of valine and leucine enantiomers. The increase in these two ratios was in agreement with that of the d -to- l ratio of lysine. The strongest relationship was observed between the increase in the d -to- l ratio of lysine and the decrease in soil microbial biomass C. However, the most stringent coherence between the increase in fallow age and soil properties was revealed by the decreases in cumulative respiration and net N mineralisation rates with decreasing availability of substrate to soil microorganisms. During the 30-day incubation following rewetting, relative changes in microbial activity (respiration and net N mineralisation) and microbial biomass (C and N) indices were similar in the eight terrace soils on a fallow age-class-specific level, indicating that the same basic processes occurred in all of the sandy terrace soils investigated.

There may be important biological sources of polycyclic aromatic hydrocarbons (PAHs) to the global environment, particularly of naphthalene, phenanthrene, and perylene, that originate in the tropics. We (i) studied the distribution of PAHs among different compartments of a typical Cerrado to locate their sources and (ii) quantified the PAH storage of this ecosystem. The sum of 20 PAH (Σ20PAHs) concentrations ranged from 25 to 666 μg kg−1in plant tissue, 7.4 to 32 μg kg−1in litterfall, 206 to 287 μg kg−1in organic soil, and 10 to 79 μg kg−1in mineral soil. Among the living biomass compartments, the bark had the highest mean PAH concentrations and coarse roots the lowest, indicating that PAHs in the plants originated mainly from aboveground sources. Naphthalene and phenanthrene were the most abundant individual PAHs, together contributing 33 to 96% to the Σ20PAHs concentrations. The total storage of the Σ20PAHs in Cerrado was 7.5 mg m−2to a 0.15‐m soil depth and 49 mg m−2to a 2‐m soil depth. If extrapolated to the entire Brazilian Cerrado region, roughly estimated storages of naphthalene and phenanthrene correspond to 7300 and 400 yr of the published annual emissions in the United Kingdom, respectively. The storage of benzo[a]pyrene, a typical marker for fossil fuel combustion, in the Cerrado only corresponds to 0.19 yr of UK emissions. These results indicate that the Brazilian savanna comprises a huge reservoir of naphthalene and phenanthrene originating most likely from the aboveground parts of the vegetation or associated organisms. Thus, the Cerrado might be a globally important source of these PAHs.

More than 90 % of the nitrogen (N) in soils can be organically bound, but the mechanisms and rates by which it is cycled have eluded researchers. The objective of this research was to contribute to a better understanding of the origin and transformation of soil organic N (SON) by using amino sugars and the enantiomers of amino acids as markers for microbial residues and/or aging processes. Studied samples presented here comprised (1) soil transects across different climates, (2) arable soils with different duration of cropping, and (3) radiocarbon-dated soil profiles. The results suggested that increased microbial alteration of SON temporarily results in a sequestration of N in microbial residues, which are mineralized at later stages of SON decomposition. Microorganisms increasingly sequestered N within intact cell wall residues as frost periods shortened. At a mean annual temperature above 12–15 °C, these residues were mineralized, probably due to limitations in additional substrates. Breaking the grassland for cropping caused rapid SON losses. Microbial residues were decomposed in preference to total N, this effect being enhanced at higher temperatures. Hence, climate and cultivation interactively affected SON dynamics. Nevertheless, not all SON was available to soil microorganisms. In soil profiles, L-aspartic acid and L-lysine slowly converted into their D-form, for lysine even at a similar rate in soils of different microbial activity. Formation of D-aspartate with time was, therefore, induced by microorganisms while that of D-lysine was not. The racemization of the two amino acids indicates that SON not available to microorganisms ages biotically and abiotically. In native soils, the latter is conserved for centuries, despite N deficiency frequently occurring in living terrestrial environments. Climate was not found to affect the fate of old protein constituents in surface soil. When native grassland was broken for cropping, however, old SON constituents had become available to microorganisms and were degraded.

Within the last 25 years an intensive agriculture has developed in the highland regions of Mato Grosso state (Brazil), which involves frequent pesticide use in highly mechanized cash‐crop cultures. To provide information on pesticide distribution and dynamics in the northeastern Pantanal basin (located in southern Mato Grosso), we monitored 29 pesticides and 3 metabolites in surface water, sediment, and rainwater of the study area during the main application season. In environmental samples, 19 pesticides and 3 metabolites were detected in measurable quantities, resulting in at least one pesticide detection in 68% of surface water samples (n= 139), 62% of sediment samples (n= 26), and 87% of rainwater samples (n= 91). Surface water samples were most frequently contaminated by endosulfan compounds (α‐, β‐, ‐sulfate), ametryn, metolachlor, and metribuzin, although in low (<0.1 μg L−1) concentrations. Sediment samples exhibited concentrations up to 4.5 μg kg−1of p,p′‐DDT, p,p′‐DDE, endosulfan‐sulfate, β‐endosulfan, and ametryn. In contrast, rainwater was polluted with substantial amounts of endosulfan, alachlor, metolachlor, trifluralin, monocrotofos, and profenofos (maximum concentrations = 0.3 to 2.3 μg L−1) in the highlands. Lowland rainwater samples taken 75 km from the next application area contained 5‐ to 10‐fold lower mean pesticide concentration than in the highlands. Cumulative deposition rates of the pesticide sum within the study period ranged from 423 μg m−2in the highlands to 14 μg m−2in the lowlands. The atmospheric input of pesticides to ecosystems seemed to be of higher relevance in the tropical study area than known from temperate regions.

This study aimed at investigating the potential of x‐ray photoelectron spectroscopy (XPS) for investigating soil organic matter at secondary soil particles. The XPS was applied to microaggregates of the A horizon of a Typic Haplustoll (<20‐μm equivalent diameter, >53‐μm maximum real diameter) and to the fine‐earth fraction (<2 mm) of the Bs horizon of a Typic Haplorthod. Carbon and N, as well as Si (both samples), Ca (Haplustoll), and Al (Haplorthod) were detected. Removing the particle surface layer (<50 nm) by bombarding with Ar+resulted in a strong reduction of the signals of C and N, while those attributed to inorganic components increased relatively. Consequently, in both soils, organic matter was concentrated at the surface of soil aggregates. We conclude that Ar+sputtering followed by XPS analysis is a useful tool in identifying the accumulation of elements at the surfaces of soil particles.

The application of a combined gas chromatography‐combustion/isotope ratio mass spectrometry (GC‐C/IRMS) method for stable carbon isotope analysis of amino acid enantiomers in soil samples is presented. Triplicate δ13C analyses of pentafluoropropionyl (PFP) isopropyl ester derivatives of 27 amino acid enantiomers revealed that discrimination of 13C during derivatization is different for different amino acid enantiomers and different amounts. Injection of increasing amounts of amino acid derivatives showed that the isotopic signal varied up to 10‰ for D‐aspartic acid. Correction for the δ13C signal of underivatized amino acid enantiomers is possible for all investigated amino acid enantiomers using logarithmic functions. Operating the GC‐C/IRMS system in the split‐mode (split ratio 1:12) is possible but resulted in a higher isotopic discrimination. The detection limit approached 3 ng for some amino acid enantiomers in the splitless mode, while the lower limit of routine determination exceeded 10 ng injection amount. The upper limit at which accurate stable isotope values were obtained was 200 ng injection amount. Compound‐specific δ13C analysis of alanine, valine, aspartic and glutamic acid showed that the D‐forms were enriched in 13C relative to the L‐forms, suggesting that microbes significantly contributed to the formation of the D‐enantiomers in soil. Copyright © 2002 John Wiley & Sons, Ltd.

Land application of animal wastes from intensive grassland farming has caused growing environmental problems during the last decade. This study aimed to elucidate the short-term sequestration of slurry-derived C and N in a temperate grassland soil (Southwest England) using natural abundance ¹³C and ¹⁵N stable isotope techniques. Slurry was collected from cows fed either on perennial ryegrass (C3) or maize (C4) silages. 50 m³ ha^—1 of each of the obtained C3 or C4 slurries (δ¹³C = —30.7 and —21.3‰, δ¹⁵N = +12.2 and + 13.8 ‰, respectively) were applied to a C3 soil with δ¹³C and δ¹⁵N values of —30.0 ± 0.2‰ and + 4.9 ± 0.3‰, respectively. Triplicate soil samples were taken from 0—2, 2—7.5, and 7.5—15 cm soil depth 90 and 10 days before, at 2 and 12 h, as well as at 1, 2, 4, 7, and 14 days after slurry application and analyzed for total C, N, δ¹³C, and δ¹⁵N. No significant differences in soil C and N content were observed following slurry application using conventional C and N analysis techniques. However, natural abundance ¹³C and ¹⁵N isotope analysis allowed for a sensitive temporal quantification of the slurry-derived C and N sequestration in the grassland soil. Our results showed that within 12 hours more than one-third of the applied slurry C was found in the uppermost soil layer (0—2 cm), decreasing to 18% after 2 days, but subsequently increasing to 36% after 2 weeks. The tentative estimate of slurry-derived N in the soil suggested a decrease from 50% 2 hours after slurry application to only 26% after 2 weeks, assuming that the increase in δ¹⁵N of the slurry plots compared to the control is proportional to the amount of slurry-incorporated N. We conclude that the natural abundance tracer technique can provide a rapid new clue to the fate of slurry in agricultural C and N budgets, which is important for environmental impacts, farm waste management, and climate change studies.

Ants are known to concentrate phosphorus (P) inside their nests via collection of food and litter. To elucidate the possible effects on long-term availability of soil P, five anthills abandoned by Red wood ant (Formica polyctena Förster) > 5—20 years ago were characterized for soil P forms in a temperate Danish deciduous forest. Sequentially extracted P fractions and liquid-state ³¹P nuclear magnetic resonance (NMR) spectra were obtained on surface samples (0—10 cm) from abandoned anthills and adjacent topsoil; in addition one representative soil profile in an abandoned anthill was investigated. The results show that different inorganic and all organic P fractions were enriched by a factor of 2.0—3.3 inside anthills relative to the surrounding soil. The soil underneath the abandoned anthill had higher P contents until 50-cm depth. Phosphorus composition was less affected by former anthill construction. Only the younger anthills revealed a preferential accumulation of labile organic P forms such as Na-HCO3 extractable P or diester P. The accumulation of the stable and moderate labile P forms, however, persisted for ≥ 20 years after abandonment. We concluded that former ant activity enhanced long-term P availability of soil due to high local P inputs, whereas changes of the P form distribution lasted 5—10 years after nest abandonment.

Among the controls on the fate of harzardous persistent organic pollutants (POPs) in the environment, soil organic matter (SOM) and climate play an outstanding role. Thus, it may be possible to predict POP concentrations at background sites from SOM properties and climatic elements. We therefore related polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) concentrations in 18 mollic epipedons under native grassland to SOM properties (lignin‐derived phenols, polycarboxylic benzoic acids [PCBAs], aromaticity, and polarity of alkali‐extractable SOM) and climatic elements. The sum of 20 PAH (∑20PAHs) concentrations ranged from 63 to 321 μg kg−1, and that of 14 PCB (∑14PCBs) concentrations ranged from 7.9 to 93 μg kg−1, except at one contaminated site (3136 μg kg−1). On average, phenanthrene (PHEN, 38% of the ∑20PAHs concentrations) and naphthalene (NAPH, 28%) were the most abundant PAHs, congeners 28 (22% of the ∑14PCB concentrations) and 101 (17%) were the most abundant PCBs. Soil organic C (SOC) concentrations correlated with the ∑20PAHs concentrations; the C concentration in the sum of eight PCBAs, a marker for black C, correlated with the concentrations of higher molecular weight PAHs, except in soils with cyric temperature regime. The ∑14PCBs concentrations was independent of any soil property. The contribution of NAPH to the ∑20PAHs concentrations and that of the up to tetra‐chlorinated PCBs to the ∑14PCBs concentrations decreased with increasing mean annual temperature (MAT). The percentages of PCB 101 increased with increasing MAT. However, the temperature effect was not strong. Mean annual precipitation (MAP) neither effected PAH nor PCB patterns. Our results indicate that the easily measured SOC concentrations may be used to predict PAH concentrations in native grassland soils of the prairie. Including MAT improves the prediction of NAPH concentrations. The influence of MAT on PCB concentrations is obvious, but the correlation is too weak to be used for reliable predictions.

Hazardous polycyclic aromatic hydrocarbons (PAHs) widely occur in the environment and are believed to be mainly anthropogenic. Here we present strong indications for large biological sources of the PAHs naphthalene, perylene, and possibly also phenanthrene in the Amazonian basin. Termite nests, plant wood, and soils were sampled. Naphthalene is detected in plant wood and is accumulated in the nests of termites from the genus Nasutitermes. Perylene is found in all studied termite nests including six different genera. Phenanthrene occurs at substantial concentrations in wood, soil, and termite nests.

During the decay of 13C enriched dung patches, the ;δ13C signal of surface soil (1–5 cm) increased with a temporary maximum after 42 d. To understand the underlying processes, we investigated the incorporation of dung‐derived C into soil particle‐size fractions. Dung, collected from beef steers fed on maize (δ13C = −15.36‰) or ryegrass (δ13C = −25.67‰), was applied in circular patches to a C3 pasture at North Wyke, UK. Triplicates were sampled from surface soil (1–5 cm) at 14, 28, 42, and 70 d after application, pooled, separated into fine (<0.2 µm) and coarse clay (0.2–2 µm), silt plus fine sand (2–250 µm), and coarse sand (250–2000 µm), and analyzed for total C, N, and δ13C. As particle‐size diameter decreased, the C/N ratios decreased and δ13C values increased at all plots due to increasing microbial alteration of soil organic matter. After dung application, ca. 60 % of dung‐derived C in soil was recovered in the 0.2–250 µm fractions during the whole experiment. The proportion of dung‐derived C in the fine clay peaked 42 d after dung application, coinciding with the δ13C maximum in the bulk soil and the maximum leaching rate measured in lysimeters at this time in another study at the same sites. The percentage of dung‐derived C as particulate C in the coarse sand fraction increased until the end of the experiment. We conclude that incorporation of C into soil from decomposing dung patches involved both temporary sorption of leached dung C to <0.2 µm fractions and continuous accumulation of particulate C (>250 µm). Copyright © 1999 John Wiley & Sons, Ltd.

During the decay of ¹³C enriched dung patches, the ;δ¹³C signal of surface soil (1–5 cm) increased with a temporary maximum after 42 d. To understand the underlying processes, we investigated the incorporation of dung-derived C into soil particle-size fractions. Dung, collected from beef steers fed on maize (δ¹³C = −15.36‰) or ryegrass (δ¹³C = −25.67‰), was applied in circular patches to a C3 pasture at North Wyke, UK. Triplicates were sampled from surface soil (1–5 cm) at 14, 28, 42, and 70 d after application, pooled, separated into fine (&lt;0.2 µm) and coarse clay (0.2–2 µm), silt plus fine sand (2–250 µm), and coarse sand (250–2000 µm), and analyzed for total C, N, and δ¹³C. As particle-size diameter decreased, the C/N ratios decreased and δ¹³C values increased at all plots due to increasing microbial alteration of soil organic matter. After dung application, ca. 60 % of dung-derived C in soil was recovered in the 0.2–250 µm fractions during the whole experiment. The proportion of dung-derived C in the fine clay peaked 42 d after dung application, coinciding with the δ¹³C maximum in the bulk soil and the maximum leaching rate measured in lysimeters at this time in another study at the same sites. The percentage of dung-derived C as particulate C in the coarse sand fraction increased until the end of the experiment. We conclude that incorporation of C into soil from decomposing dung patches involved both temporary sorption of leached dung C to &lt;0.2 µm fractions and continuous accumulation of particulate C (>250 µm). Copyright © 1999 John Wiley & Sons, Ltd.

Zonale Böden aus ähnlichem Ausgangsmaterial eignen sich zur Untersuchung der Frage, ob und in welchem Umfang Klimafaktoren die organische Bodensubstanz beeinflussen. Hierzu wurden von 10 ungestörten, zonalen Steppenböden Rußlands Ober- (0—10 cm) und Unterbodenhorizonte (ca. 50—60 cm) beprobt. Anschließend wurden Polysaccharide sowie Vanillyl-, Syringyl- und Cinnamyleinheiten (VSC) von Lignin in der Feinerde und den Partikelgrößen-Fraktionen Ton (&lt; 2 μm) und Schluff (2—20 μm, gemäß ISSS-Klassifikation) bestimmt. Mit fallendem Quotient aus mittlerem jährlichem Niederschlag und potentieller Verdunstung (= N/V) nehmen im Unterboden die Polysaccharidgehalte tendenziell ab. In der Schlufffraktion ist die Abnahme der Zucker mit fallendem N/V am deutlichsten ausgeprägt (r = 0,98**). Die auf organisch C bezogenen VSC-Gehalte nehmen hingegen im Unterboden mit abnehmendem N/V zu (r = —0,92**). Dies hat zur Folge, daß mit fallendem N/V die VSC/Zucker-Verhältnisse des Unterbodens ansteigen (r = —0,94*). Vermutlich werden bei höherer Durchfeuchtung der Böden (weites N/V-Verhältnis) relativ mehr mikrobielle Zucker im Unterboden produziert oder dorthin verlagert als bei geringerer Durchfeuchtung der Böden, wo aufgrund verstärkter C-Mineralisation Lignin selektiv angereichert werden kann.

Concentrations and forms of AI and heavy metals in aggregate core and surface fractions of forest soils in Central Europe differ significantly. The objectives of this study were to (i) test if there is a similar small‐scale metal heterogeneity in topsoils of the native North American prairie and (ii) investigate the influence of climatic parameters on this heterogeneity. Aggregates of eight A horizons along a climatic transect in the North American prairie were separated into core and 0.5‐mm‐thick surface fractions. Seven forms of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined in the aggregate fractions using a sequential extraction procedure. The differences of metal concentrations between aggregate surface and core fractions are 1 to 25% of the total concentrations of the core fractions. The percentages of easily extractable metals are up to 120% higher in the aggregate surface than in the core fractions. The percentages of the mainly silicate‐bound metals (extractable only with strong acids) are up to 25% lower than in the core fractions. These results support the hypotheses that (i) preferential weathering of aggregate surfaces causes a shift from strongly to more weakly bound metal forms and (ii) atmospheric metal input is sorbed preferentially at the aggregate surfaces, and (iii) this input is weakly bound only. Lead is significantly enriched in the surface fractions compared with the cores, indicating ubiquitous input of Pb to the soils. The depletion of the mainly silicate‐bound metals in the aggregate surface fractions compared with the core fractions correlates with the mean annual temperature and the mean annual precipitation, which both favor silicate weathering.

Characterizing the amino sugar signature in particle-size fractions allows elucidation of the fate of microbially derived compounds during the alteration and turnover of soil organic matter (SOM) in soils of different climate regimes. The purpose of this study was to evaluate amino sugar pools and the effect of climate on such pools in particle-size fractions of 18 surface (0-10 cm) soil samples along a climosequence in the native North American prairie. Soils were fractionated into clay (<2 μm), silt (2-20 μm), fine sand (20-250 μm), and coarse sand (250-2000 μm). Soil organic carbon, glucosamine, mannosamine, galactosamine, and muramic acid were then determined in the fractions.